This application claims the priority of Korean Patent Application Nos. 2003-84963 and 2004-35534, filed on Nov. 27, 2003 and May 19, 2004, respectively, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein in their entirety by reference.
1. Field of the Invention
The present invention relates to a field emission display and, more particularly, to a field emission display having an emitter structure that improves focusing characteristics of electron beams, thus improving image quality.
2. Description of the Related Art
Display devices, which account for one of the most important parts of conventional data transmitting media, have been used in personal computers and television receivers. The display devices include cathode ray tubes (CRTs), which use high-speed heat electron emission, and flat panel displays, such as a liquid crystal display (LCD), a plasma display panel (PDP), and a field emission display (FED), which have been rapidly developing in recent years.
Of those flat panel displays, an FED is a display device that enables an emitter arranged at regular intervals on a cathode electrode to emit electrons by applying a strong electric field to the emitter to radiate light by colliding the electrons with a fluorescent material coated on the surface of an anode electrode. Since the FED forms and displays images thereon by using the emitter as an electron source, the quality of the images may vary considerably depending on the material and structure of the emitters.
Early FEDs use a spindt-type metallic tip (or a micro tip) formed of molybdenum (Mo) as an emitter. In order to arrange such metallic tip-type emitter in an FED, however, an ultramicroscopic hole should be formed, and molybdenum should be evenly deposited on the entire surface of a screen, which requires the use of difficult techniques and expensive equipment and thus results in an increase in manufacturing costs. Therefore, there is a clear limit in manufacturing a wide screen FED.
In the industry of FEDs, research on methods of forming a flat emitter of an FED, which can emit sufficient amounts of electrons even at a low driving voltage and, eventually, can simplify processes of manufacturing the FED, is under way. Current trends in the FED industry show that carbon-based materials, for example, graphite, diamond, diamond-like carbon (DLC), fulleren (C60), or carbon nano-tubes (CNTs), are suitable for the manufacture of a flat emitter and the CNTs, in particular, are considered most desirable because they can successfully emit electrons even at a low driving voltage.
In order to have an FED display images of good quality, the electron beam emanating from the emitter must be focused and must not disperse too much so that only the phosphor layer in the intended pixel and not phosphor in neighboring pixels are impacted by the electron beam. Therefore, what is needed is an FED with superior image quality brought on by an improved design of the emitter so that the electron beam emanating from the emitter is focused and does not disperse too much so that the electron beam hits phosphor in the desired pixel and not phosphor in neighboring, unintended pixels.